The present invention relates generally to prosthetic implants, and particularly to dental implants that are designed to distribute forces, created during mastication, to surrounding bone. This distribution of forces reduces stress shielding of the surrounding bone.
A variety of dental implants currently are known and available. The implants are designed for insertion into the maxilla or mandible, e.g. jawbone, of a patient to support the mounting of a prosthetic tooth. Generally, a cylindrical hole is formed in the mandible or jawbone of the patient, and the implant is mounted in the hole and allowed to undergo osseointegration.
A dental implant includes a generally cylindrical body designed for placement in the cylindrical hole formed in the jawbone of a patient. The generally cylindrical body may be threaded. The exposed or coronal end of the dental implant includes a mounting feature or features that aid in the mounting of a prosthetic tooth. For example, the coronal end may include a splined interface and a threaded bore to which an abutment and prosthetic tooth are ultimately mounted.
Conventionally, the body of the dental implant has been formed from titanium or a titanium alloy, such as Ti6A14V. Such titanium materials have served well in enhancing bone attachment to the surface of the dental implant. It is believed that a stable oxide forms on the titanium or titanium alloy, and serves as a suitable surface for enhancing the desirable attachment between bone and the dental implant.
Despite their proven record in promoting osseointegration, titanium and titanium alloys present certain other challenges to providing an optimal dental implant. Titanium and suitable titanium alloys are orders of magnitude higher in stiffness than human bone, and therefore dental implants formed from such materials absorb most of the forces of mastication. This can lead to a phenomenon known as Astress shielding of the surrounding bone.
Specifically, it has been determined that inadequate stimulation of bone tissue over extended periods causes the bone tissue to be resorbed by the body, an effect commonly known as Wolff?s Law. This effect becomes apparent when bone surrounding the dental implant is not adequately stimulated due to, for instance, absorption of a majority of forces created during mastication by a stiff dental implant. The lack of stimulation can cause saucerization, otherwise known as bone die-back, which progresses around the upper portion of an otherwise healthy dental implant. The loss of bone can lead to destabilization and even loosening of the dental implant. Additionally, once sufficient bone tissue has undergone resorption, portions of the implant body become exposed, and this surface, which is typically extured to provide high surface area, is susceptible to infection.
It would be advantageous to design a dental implant able to transmit the forces of mastication to surrounding bone tissue without being unduly subject to degradation or breakage.
The present invention features a dental implant comprising an implant body. The implant body includes a metallic core and an anti-rotational mounting feature connected to the metallic core. Additionally, a shell is disposed about the metallic core. The shell has a lower modulus of elasticity than the metallic core to facilitate transfer of force to surrounding bone tissue.
According to another aspect of the invention, a dental implant is designed for implantation at an implant site in a maxilla or mandible of a patient. The dental implant comprises a metallic core and a shell. The shell includes a recessed opening sized to receive at least a portion of the metallic core. The shell includes an outer surface sized to fit within a cylindrical hole formed in the mandible at the implant site. Additionally, the shell is formed of a less stiff material than the metallic core to facilitate transfer of forces from the dental implant to the surrounding bone tissue.
According to a further aspect of the invention, a dental implant is provided for implantation at an implant site which includes a cylindrical hole formed in a mandible or maxilla of a patient. The dental implant comprises a mounting end to which a prosthetic tooth can be attached. Additionally, a force dissipater is coupled to the mounting end. The force dissipater is sized for insertion into the hole formed in the mandible. This force dissipater effectively distributes a substantial portion of the forces, generated during mastication, to the mandible surrounding the force dissipater.